Condenser



June 3, 1924. 1,496,371

C. B. GRAVES CONDENSER Filed Aug. 23. 1922 Patented June 3, 1924.

UNITED STATES CHARLES B. GRAVES, OF MARBLEHEAD, MASSACHUSETTS.

CONDENSER.

Application filed August 23, 1922. Serial No. 583,736.

will be so constructed as to provide a varia tion in capacity of the condenser by compressing the several plates and the dielectrio.

A further object of the invention is to provide a suitable variable condenser for receiving or transmitting radio signals in which the conductor plates are sliced or notched out to eliminate eddy currents.

Another object of the invention is to provide a suitable variable condenser for radio telegraphy or telephony which will be so constructed as to produce avariable capacity in the condenser b compressing the several 30 plates and the die ectric, and which will be formed to include a plurality of separate condenser units within a single casing or housing, each unit being adjustable independent of the others.

A still further object of the invention is to provide a suitable variable condenser which will combine the highest possible degree of efficiency in operation with the least expense in manufacture.

Other objects will appear as the description proceeds.

In the accompanying drawings, which constitute a part of this application:

Fig. 1 is a side elevation of my improved variable condenser;

Fig. 2 is an end elevation of the variable condenser;

Fig. 3 is a top plan view of the variable condenser;

Fig. 4 is a sectional view taken on the line 44 of Fig. 3, and

Fig. 5 is a view of one of the slotted cong uctor plates taken on the line 5-5, of

Like characters of reference are used provide a suitable variable condenser, which throughout the following specification, and the drawings, to designate corresponding parts.

The variable condenser is provided with a base portion 1 to which are attached a plurality of spaced vertically extending partitions 2. A suitable reinforcin bar or frame 3 connects the outer ends the partitions 2, and serves to strengthen the structure.

Positioned between the partition plates 2 are the several elements which form the electrical part of the condenser, namely, a layer or sheet of insulating material 4, a metallic plate 5, the dielectric 6 which is preferably of mica, a slotted or grid-like metallic plate 7, and a layer or sheet of insulating material 8. The sheets of insulating material 4 and 8 are preferably of oil paper or the like, although any suitable insulating material may be used. The metallic conductor plate will be formed of brass or aluminum, or of whatever mate'rial proves to be most desirable. The conductor plate 7 is preferably formed from heavy tinfoil or from a thin aluminum sheet, and is notched out Or cut away to provide the parallel spaced fingers or ribs 9. This notching or slicing of the metallic plate is done to eliminate the eddy currents which are so numerous in radio circuits, and is of greatest importance to the efiicient working of the condenser.

It will be understood that the electrical units of the condenser 4, 5, 6, 7 and 8, will be positioned between each of the partitions 2 and fit loosely therein It is desired to make the unit 10 completely fill up the space between the first two of the partitions 2, as shown in Fig. l of the drawings, while unit 11 fills up one-half of the space between the remaining two partitions, and unit 12 fills up one quarter of the space between the last mentioned partitions. Thus it will be seen that within a single casing or housing there will be three separate and distinct condensers having three separate and distinct normal capacities.

Positioned between the partitions 2 and the units 10, 11 and 12, are the followers of bulkheads 13, 14 and 15, to which are swivelly mounted the operating screws 16, 17 and 18, the same passing through suit able bushings 19 in the partitions 2. Hard rubber or insulating handles 20 are attached to the outer ends of the screws 17,

18 and 19 to completely insulate the hand of the person operating the condenser fr m the metallic circuit.

A plurality of binding posts 21 are positioned on the base 1 and are connected respectively with the separate metallic eonductor plates 5 and 7 by means of wiring 22.

Since the units 10, 11 and 12 fit loosely in between the partitions 2 it will be seen that by tightening up on the knobs 20 the followers 13, 14 and 13 will compress the several units so that the plates and the .dielectric can be compressed as much as desired. Assuming that the capacities of the separate units was at one reading when the several parts of each unit were loosely held in place, it will be apparent that when these separate elements were compressed that the capacities of the said units would be increased since the varying of the tension or compression of the dielectric serves to increase the capacity of the condenser in which it is used.

It is known and understood that the compression of the dielectric has been used in high voltage transmission condensers where compressed air serves as the dielectric. and since the charge resides on the dielectric it is thought that it is an entirely new idea to vary the capacity of the variable condenser by varying the tension or compression of the dielectric in the said condenser by a considerable manual effort so that the change in capacity will be relatively small.

The slicing or notching of the conductor plates increases the efiiciency of the condenser, as it eliminates many paths for eddy currents which are a loss and are uncontrollable.

In the usual type of variable condenser it is customary to vary the position of the movable plates within the stationary plates to bring in the incoming signals as desired; however, with my variable condenser I obtain this adjustment and also vary the capacity of the condenser proper by varying the tension or compression of the dielectric.

Many minor changes in detail of constructionmay be resorted to without departing from the spirit of the invention.

Having thus described my invention I claim and desire to secure by Letters Patent:

'1. A variable condenser comprising a plurality of plates notched out to provide parallel spaced ribs. associated insulating material. sheets of dielectric material between said plates. and means for compressing said plates and material for varying the capacity of said condenser.

Q. A variable condenser comprising groups of notched-out plates to provide a. plurality of parallel spaced fingers or ribs, dielectric sheets positioned between said lates, and a plurality of imperforate plates alternately positioned between said notchedout plates and separate means for varying the capacity between the plates of the several groups.

In testimony whereof I afiix my signature.

CHARLES B. GRAVES. 

